In circular knitting machines, the thread-delivery system has two or more belts, and two arrangements for the thread-delivery rollers and the associated cut-off devices are presently known.
In the one known arrangement U.S. Pat. No. 3,264,845, the delivery roller and the cut-off device are connected as one structural unit. The cut-off device has a cylindrical housing, which is arranged coaxially with respect to the thread-delivery roller and is connected to same. However, the unitary thread-delivery roller--cut-off device has a high height, so that the thread-delivery system occupies much space in the vertical direction. This is particularly true when the thread-delivery roller--cut-off device--units are each supported on separate support rings. However, the same problem will occur in a slightly lesser degree even when the thread-delivery rollers are supported with the cut-off devices which are connected to them on vertical posts, which are all mounted on a common support ring (U.S. Pat. No. 3,785,176). In the latter case each post carries only one thread-delivery roller with associated cut-off device. Idling rollers are arranged on a post which is parallel thereto for the belts which are not in contact with thread-delivery rollers. This arrangement has, as mentioned, as regards height, a slightly lesser need for space; however, it is difficult to store sufficient thread-delivery units in the peripheral direction of the machine, when dealing with a multi-system circular knitting machine.
The other known arrangement consists in supporting the thread-delivery rollers alone on vertical posts which are held by only one single support ring and to mount cut-off devices, which are structurally totally separate from said rollers, on a further support ring, which is provided below the aforementioned support ring. The space separation of the cut-off devices from the thread-delivery rollers has the great disadvantage that during stopping, the thread cannot be moved out of its clamped position between the belts and the thread-delivery rollers. Due to the inertia of the machine during stopping, after the switching-off time, still a large amount of thread is delivered, which can result in complications when the machine starts again.
The basic purpose of this invention is to produce an apparatus of the above-discussed type which permits a compact and space-saving arrangement of the thread-delivery rollers and of the cut-off devices while maintaining the advantages of a moving out of the thread from the clamping position during stopping.
This purpose is attained by the invention as defined in the attached claims.
In the case of the inventive apparatus it is possible to support a number of thread rollers, equal to the number of belts as exist on the machine, one above the other on a center support shaft. Since only the structural height of the thread-delivery rollers themselves is to be absorbed, the need for space in the elevational direction is small. The cut-off devices are supported as separate structural units on a guide bar which is parallel with respect to the shaft. As many cut-off devices are mounted on the guide bar as thread-delivery rollers are provided. Due to the narrow space and close association of the cut-off devices and the thread-delivery rollers, it is possible to maintain the function of moving the thread out from the belt during stopping. The guide bar extends near the shaft and the thread-guiding rollers and the cut-off devices are arranged closely side-by-side. This makes the entire apparatus extremely compact. By moving the cut-off devices on the guide bar, the moving-out function can be adjusted simply. Thus an apparatus is created which permits, in multi-system circular knitting machines, storage of the entire thread-delivery system in the smallest space.
It is already known to support on a vertical post, which is held on a support ring by clampable brackets, thread-delivery rollers and idling rollers and to arrange by means of a further bracket which projects in the other direction a cut-off device approximately at the same height as the thread-delivery roller. This cut-off device forms its own structural unit which is totally independent from the thread-delivery roller and which does not effect a moving of the thread out of the clamping position during stopping. Furthermore, with this system it is possible to provide only one cut-off device, so that an arrangement of several thread-conveying rollers one above the other on the same post and associated with cut-off devices which lie at the same level is not possible (Terrot-brochure).
The guide bar of this invention can be advantageously arranged radially inwardly of the respective support shaft as viewed relative to the support ring of the knitting machine. This results in an advantageous thread delivery and removal. The space which is available on the periphery of the support ring is utilized to an optimum.
In a preferred embodiment the guide bar is constructed as an electrically insulative member with electrically conductive paths in the longitudinal direction thereof, and each cut-off device has sliding contacts on walls of a guide groove which grips around the guide bar. The guide bar thus performs a second function. It eliminates the need for additional electrical lines to and from the cut-off devices. The entire structure becomes simpler and thus also less susceptible to breakdown. The electrical current connection of each cut-off device is without problems and is created independently from the respective adjusted height.
The insulating member of the guide bar can advantageously form a long narrow rectangle in cross section with two recesses which are arranged spaced from one another and which define parallel longitudinal grooves on one longitudinal side, and with projecting edge strips on the other longitudinal side. The edge strips have on their free ends inwardly projecting noses. Electrically conductive bars are supported in the longitudinal grooves and between the edge strips. Three conductive paths to the cut-off devices, which paths are independent from one another, are thus obtained on the surface of the guide bar. These paths can be used for the current supply and for transmitting of signals, i.e. switching functions. At the same time the narrow bar shape, which is advantageous for the longitudinal movement of the cut-off device, is maintained, so that the associated open or closed guide groove on the cut-off device does not unfavorably influence its structural size. The guide bar can be manufactured in an economical manner: either the conducting paths can be cast or sprayed in directly during the manufacture of the insulating member, or can be fixedly engaged in the provided recesses or between the noses of the edge strips.
The conductive bars can be connected in a simple manner to an electrical supply line which extends in the area of the support ring such that the conductive bars have, on their ends which are near the support ring, bent contact edges which project approximately horizontally from the insulating member. During attaching of the holder on the support ring, the contact edges can directly pierce through the insulation of a supply line and create the desired contact.